From the great complexity of the composition of animal substances,
their decomposition is more rapid and its products more diverse than
in the case of organic bodies of vegetable origin. While the carbon,
hydrogen and oxygen give origin to the various kinds of ulmine and
other substances of the same class, the nitrogen is generally valued
as ammonia, and the sulphur as sulphurated hydrogen. It is the
presence of these bodies that give to the putrefying substances the
disagreeable odors by which that process is distinguished from mere
mouldering and rotting.
Even during life, the constituent particles of the body are in a
continual state of change, being absorbed and thrown out of the
system, while others are assimilated in their place. Any part of our
constituents, liquid or solid, which become unfitted for this vital
function, is thereby killed, and must, if not got rid of, induce the
death of the individual.
Hence, precisely the same means which give to the animal substances
the fixity of constitution which belongs to true chemical compounds,
and thus preserve them from decomposition by the disturbing action
of their own elements (as when we coagulate albumen by an acid, by
corrosive sublimate, or by sulphate of copper), produce if applied to
the living body the death of the part or the whole being by depriving
the blood or the tissue of the mutability of constitution, which is
required for the functions of the animal frame.
It is thus that the generality of metallic poisons act in producing
death. Being absorbed into the system, they unite with the albumen
and fibrine of the blood, and converting them into the insoluble
compounds which we form in the laboratory, unfit them for the
continual absorption and secretive offices, which, as organs, while
they live they must fulfill. If the injury be local and limited in
extent, the part so coagulated may be thrown off, and after a certain
time the functions return to their proper order. If the mass, or the
importance of the affected parts be greater, the system cannot so get
rid of the portions which have thus been removed from the agency of
life, to submit to merely chemical laws; on the contrary, the vital
powers of the remaining portions of the animal are so much weakened
in the effort that general death is caused.
For putrefaction it is thus necessary: 1st. That the force of
vitality which governs so completely the mere chemical tendencies of
the elements of our tissues be removed.
2d. That there shall not be present any powerful chemical reagent
with which the organized material matter may enter into combination
and thus the divellent tendencies of the affinities of its elements
be overcome.
3d. That water be present in order to give the necessary mobility.
4th. That oxygen be present, or at least some other gas, into the
space occupied by which the gaseous products may be diffused; and
lastly, that the temperature shall be within moderate limits,
putrefaction being impossible below 32° or above 182°.
The agency of the first of these preventive powers need not be
further noticed. The second is extensively employed for embalming
purposes, and in the preparation of bodies for anatomical studies,
by baths, or injections into the arteries of solutions of corrosive
sublimate, acetate of alumina, sulphate of iron, tannin, wood
vinegar, and creasote; this last body, however, does not appear
to act by direct combination, but by the complete (catalytic)
coagulation it produces in all the tissues of the body that have
protein for their base.
The necessity for the presence of water is shown by the fact that by
drying the animal substances they are completely preserved. It is
thus that the bodies of those perishing in the Arabian deserts are
recovered years subsequently, dried, but completely fresh.
Alcohol and common salt both act in the preservation of bodies
by their affinity for water. If a piece of flesh is covered with
salt, the water gradually passes from the pores of the flesh, and
dissolving the salt forms a brine, which does not wet the flesh, but
trickles off its surface; the water necessary for putrefaction is
thus removed.
Fourth, by excluding oxygen, the putrefactive process is retarded,
precisely as the fermentative action of the gluten in grape juice
cannot begin until a certain quantity of oxygen be absorbed. It is
thus that meat that is sealed up in close vessels and then boiled
for a moment is preserved; the small quantity of oxygen of the air
remaining then in the vessel is absorbed, and the produce of that
minute change being coagulated by heat it cannot proceed farther.
A high temperature stops putrefaction by coagulating the azotized
materials; a temperature below 32° by freezing the water acts as if
the tissues had been dried; in both cases putrefaction is arrested.
During putrefaction, at a stage prior to any fetid gas being evolved,
a peculiar organic substance is generated, _possessed of intensely
poisonous properties, and the blood of persons who have died from its
effects is found to be quite disorganized and irritating when applied
to wounds_.
This and the blood of over-driven cattle are found to produce effects
similar to those of venomous reptiles, and the wounds received in
dissection are sometimes followed by similar fatal consequences.
The communication of disease in this way has recently been very
ingeniously ascribed by Liebig to the general principle of the
communication of decomposition by contact.
The small quantity of diseased organic matter originally introduced
into the system by absorption, acts as a ferment and reproduces
itself in the mass of the blood, until this becomes unfitted for the
performance of its functions and the animal is killed; the active
principle being thus copiously present, is exuded from the skin
and lungs and gives a contagious character to the disease, or it
remains only in the blood, or is secreted in _pustules_, constituting
infection, by which the disease may be communicated to some other
person.
This brief enumeration of the process of putrefaction will, to a
certain extent, elucidate the process of embalming given in this
book; it shows that the different methods herein explained, fulfill
the conditions necessary to stop the progress of decomposition.
A most important point, and one which ought not to be passed upon
without serious consideration is, the communication of disease by
contact and absorption.
In a former part of this work, it has been suggested that too much
care cannot be used in handling the bodies of persons who have died
of certain diseases, especially when their bodies are to be subjected
to the embalming process, which operation is rendered extremely
dangerous to the embalmer from the fact that the hands must,
perforce, come into direct contact with the denuded tissues, the
blood, or some vitiated secretion of the body.
We shall, in the following chapter, find instances when the
decomposition of certain parts of the body has taken place even
before death. It is obvious that in such cases the utmost caution is
necessary to avoid serious results.